Subj : instanceof XML and instanceof XMLList?
To   : netscape.public.mozilla.jseng
From : Martin Honnen
Date : Mon Mar 28 2005 06:11 pm


I have found the following differences between Spidermonkey:

js> var xmlObject = new XML('<gods><god>Kibo</god><god>Xibo</god></gods>');
js> xmlObject instanceof XML
true
js> xmlObject instanceof XMLList
true

and Rhino:

js> var xmlObject = new XML('<gods><god>Kibo</god><god>Xibo</god></gods>');
js> xmlObject instanceof XML
true
js> xmlObject instanceof XMLList
false

Thus Spidermonkey says the object created with new XML() is instanceof 
XML and instanceof XMLList at the same time while for Rhino it is only 
instanceof XML but not XMLList.

So far each time I try to figure whether something is an XML object or 
an XMLList object and turn to the E4X specification I end up in a 
section saying something alike "This intentionally blurs the distinction 
between XML objects and XMLLists".

In the above test case not even the implementations agree. Which 
implementation is right in the above test case? Or is Spidermoney doing 
something different in the prototype chain but both ways are allowed?

-- 

	Martin Honnen
	http://JavaScript.FAQTs.com/

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